COMPLEX DIMPLE GEOMETRY FOR IMPROVED PLATE-FIN HEAT EXCHANGER

Description

CROSS-REFERENCE TO RELATED APPLICATION

The present disclosure claims the benefit of Provisional Patent Application No. 63/637,526, filed on Apr. 23, 2024 and entitled “COMPLEX DIMPLE GEOMETRY FOR IMPROVED PLATE-FIN HEAT EXCHANGER HTC”, the contents of which are incorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a heat exchanger for improving heat transfer. In embodiments, the present disclosure relates to a heat sink with dimples.

BACKGROUND

The performance, lifespan, and safety of many electrical components are dependent on the temperature at which the electrical components operate and a build-up of heat can negatively affect these elements. The temperature of the electrical component may be affected by heat generated from the electrical component or its surrounding environment. Heat sinks are used to dissipate heat from electrical components or other heat-generating devices and prevent the negative effects from a build-up of heat. Some heat sinks use plate fins or pin fins that extend outward from a base that is in thermal communication with the electrical component. As fluids (e.g., air, water, or the like) flow along the heat sink through the fins, the fins transfer the heat from the electrical component to the fluid, cooling the electrical component.

Heat transfer from the heat sink to the fluid can be improved by increasing the surface area of the heat sink. Increasing the surface area of the heat sink typically improves the conductive and convective heat transfer of the heat sink. However, an increase in the surface area of the heat sink can also disrupt the flow of the fluid and result in a diminished convective heat transfer efficiency and a greater pressure drop.

SUMMARY

Described herein is in an embodiment of a heat sink for improving heat transfer efficiency. A heat sink including a substrate having an upper surface. A plurality of fins extends outwardly from the upper surface. The plurality of fins extend from a base to a tip and a fin height is defined by a distance between the base and the tip. A plurality of dimples are round and 3D-printed. The plurality of dimples are located between the plurality of fins or on the plurality of fins.

Another embodiment of the heat sink includes a substrate with a first side and a second side opposite the first side. A plurality of fins extend outwardly from the upper surface along a longitudinal direction from adjacent the first side to adjacent the second side. A plurality of dimples include side surfaces that converge to a peak and have a parabolic shape. The plurality of dimples are located on the upper surface between the plurality of fins or on a surface of the plurality of fins. The plurality of dimples are 3D-printed dimples.

Another embodiment of the heat sink includes a substrate having an upper surface, a first side, and a second side opposite the first side. A plurality of fins extend outwardly from the upper surface along a longitudinal direction from adjacent the first side to adjacent the second side. The plurality of fins extend from a base to a tip and a fin height is defined by a distance between the base and the tip. The substrate defines a first set of dimples located on the upper surface between the plurality of fins. The first set of dimples have a dimple height less than 30% of the fin height. The plurality of fins define a second set of dimples on a surface of the plurality of fins that is less than 30% of the fin height or above 70% of the fin height.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a traditional heat sink with plate fins, according to the prior art;

FIG. 2 is a top view of a traditional heat sink with pin fins, according to the prior art;

FIG. 3 is a cross-sectional side view of a heat sink with straight plate fins and spherical dimples, according to an embodiment of the present disclosure;

FIG. 4 is a top view of a heat sink with nonlinear plate fins and spherical dimples arranged in various patterns, according to an embodiment of the present disclosure;

FIG. 5 is a top view of a heat sink with pin fins and spherical dimples, according to an embodiment of the present disclosure;

FIG. 6 is a side perspective view of the heat sink shown in FIG. 5;

FIG. 7 is a cross-sectional side view of the heat sink shown in FIG. 3 with parabolic dimples, according to an embodiment of the present disclosure;

FIG. 8A is a top view of an airfoil dimple, according to an embodiment of the present disclosure;

FIG. 8B is a top view of an airfoil dimple, according to an embodiment of the present disclosure;

FIG. 8C is a top view of an airfoil dimple, according to an embodiment of the present disclosure; and

FIG. 8D is a top view of an airfoil dimple, according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments can take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative bases for teaching one skilled in the art to variously employ the embodiments. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures can be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical application. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations.

“A”, “an”, and “the” as used herein refers to both singular and plural referents unless the context clearly dictates otherwise. By way of example, “a processor” programmed to perform various functions refers to one processor programmed to perform each and every function, or more than one processor collectively programmed to perform each of the various functions.

As shown in FIGS. 1 and 2, according to the prior art, a heat sink 10 for dissipating heat from a device capable of generating heat (e.g., an electrical or computer component, an inverter card, or the like) includes a substrate 12 with an upper surface 14. The heat sink 10 may be attached to the device via the outer plate, a thermal paste, a connecting component between the heat sink 10 and the device, or the like. The heat sink 10 may also be connected to a housing (e.g., via an outer plate surrounding the substrate 12) that encloses the heat sink 10 for containing and exposing the substrate 12 to a fluid, such as water, air, refrigerant, oil, dielectric fluid, or some other non-conductive thermal transfer fluid, or the like. The fluid is conveyed (by forced or natural convection) through the heat sink 10 from a first side 16 to a second side 18 opposite the first side 16, as indicated by the fluid flow F.

Fins 20 extend outwardly from the upper surface 14 of substrate 12 from a base 22 to a tip 24 and along the substrate 12 from the first side 16 to the second side 18. The fins 20 may be plate fins, pin fins, or the like. In some embodiments, the fins 20 are plate fins arranged in rows 26 along a longitudinal direction and the fluid flows between the fins 20. The fluid flows between the fins 20 and may recirculate in a space between the fins 20. In some embodiments, the fins 20 are pin fins arranged in uninform or non-uniform rows 26, a staggered arrangement, or the like. The rows 26 of the plurality of fins 20 define channels 27 (e.g., a space for the fluid to flow between at least two rows 26 of the plurality of fins 20) for the fluid to flow from the first side 16 to the second side 18. The pin fins may have a shape including an elliptical, an airfoil, a tear-drop, a circular, a conical, a rectangular, a parabolic, or other known shapes, or the like, or a combination or sub-combination thereof.

Referring to FIG. 3-7, an embodiment of the heat sink 10 includes a plurality of dimples 28 protruding from the upper surface 14 of the substrate 12 (i.e., extending outwardly from the substrate 12). In some embodiments, the substrate 14 defines the plurality of dimples 28. The plurality of dimples 28 may include a variety of shapes or cross-sectional areas. In some embodiments, the substrate 12 defines the plurality of dimples 28 having a convex shape relative to the upper surface 14. In other words, the plurality of dimples 28 may have a shape that is spherical or round relative to the upper surface 14 (e.g., hemispherical, semispherical, or the like). The plurality of dimples 28 are disposed in between or amongst the fins 20 and/or in the rows 26. In some embodiments, the plurality of dimples 28 are disposed adjacent to or spaced apart from the base 22 of the fins 20. For example, the plurality of dimples 28 may be in close proximity to the base 22 of the fins 20 or may be positioned centrally in the rows 26 between the fins 20.

The plurality of dimples 28 increases the surface area of the heat sink 10 along the substrate 12 for improving the overall heat transfer coefficient. The increase in surface area of the heat sink 10 reduces the thermal resistance for conduction. Because conduction through the heat sink 10 can be a bottleneck for improvement to thermal performance, a reduction in the thermal resistance for conduction leads to a decrease in the total thermal resistance of the heat sink 10. Furthermore, the relative fluid flow velocity is at its lowest adjacent the substrate 12 and/or base 22 of the fins 20 such that the increase in the surface area of the heat sink 10 does not result in a significant increase in pressure drop across the heat sink 10. In other words, while the plurality of dimples 28 may disrupt the fluid flow velocity along the substrate 12, the disruption may increase the convective heat transfer coefficient without a significant increase in pressure drop. For example, the plurality of dimples 28 may not result in a significant increase of flow separation and/or reversal of the fluid flow velocity.

Referring to FIGS. 3 and 4, in an embodiment of the heat sink 10 the plurality of dimples 28 may be arranged in a uniform or non-uniform arrangement or pattern along the substrate 12. The arrangement of the plurality of dimples 28 may be staggered or include at least one row 32 and/or column 33, or a plurality of rows 32 or columns 33, or the like. For example, at least one channel 27 of the fins 20 may have a first pattern 30a including a first row 32a and a second row 32b of the plurality of dimples 28 that are in a staggered arrangement. In another example, at least one channel 27 of the fins 20 may have a second pattern 30b including a single row 32 of the plurality of dimples 28 positioned centrally within the at least one channel 27. In yet another example, at least one channel 27 of the fins 20 may have a third pattern 30c including the first row 32a and the second row 32b of the plurality of dimples 28 that are aligned relative to each other, resulting in columns 33 defined by the first row 32a and the second row 32b. The arrangement of the plurality of dimples 28 may be chosen based on the criterion including heat transfer, fluid dynamics, pressure drop, manufacturability, or the like. In some embodiments, the plurality of dimples 28 includes a first group of the plurality of dimples 28 and a second group of the plurality of dimples 28, wherein the first group of the plurality of dimples 28 are arranged in the first pattern 30a within a first channel 27, and the second group of the plurality of dimples 28 are arranged in the second pattern 30b within the second channel 27, wherein the second pattern 30b is different from the first pattern 30a (the first pattern 30a and/or the second pattern 30b could be substituted with the third pattern 30c or another pattern, or the like).

In an embodiment, the arrangement of the plurality of dimples 28 may be uniform or discontinuous between at least two rows 26 of the fins 20 and/or within at least one channel 27. In other words, at least one channel 27 may include a plurality of arrangements of the plurality of dimples 28 and/or a combination of the first arrangement 30a, the second arrangement 30b, and/or the third arrangement 30c. For example, at least one channel 27 may include the first arrangement 30a from adjacent the first side 16 to a point between the first side 16 and the second side 18 and the second arrangement from the point between the first side 16 and the second side 18 to adjacent the second side 18.

Referring to FIGS. 5 and 6, in an embodiment of the heat sink 10 the plurality of dimples 28 may partially or fully extend from the fins 20 adjacent the base 22 of the fins 20. In other words, the plurality of dimples 28 may extend from the fins 20 and not the substrate 12 or may extend from both the fins 20 and the substrate 12 at approximately the base 22 of the fins 20. The plurality of dimples 28 may extend from any point along an outer surface of the fins 20 and/or a perimeter defined by the base 22 of the fins 20. For example, where the fins 20 are pin fins with an elliptical shape the plurality of dimples 28 may extend from the fins 20 along the perimeter from one vertices to another. In some embodiments, the heat sink 10 includes fins 20 that are elliptical pin fins arranged in staggered rows 26 along the substrate 12 such that a first end or vertices 34a of a first fin 20a is adjacent a second end 34b of second fin 20b, wherein the at least one of the plurality of dimples 28 extends from the first fin 20a adjacent the first end 34a. In some embodiments, the heat sink 10 includes a plurality of dimples 28 extending from the outer surface of at least one of the fins 20.

In an embodiment, the plurality of dimples 28 extend from the upper surface 14 of the substrate 12 in a gap 36 defined by the arrangement of the fins 20. The gap 36 may be an area for fluid to flow through, between, and/or amongst the fins 20. For example, where the fins 20 include rows 26 of elliptical pin fins in a staggered arrangement in a longitudinal direction, the gap 36 may be a location or space between or adjacent to the ends of two adjacent fins 20 in a common row 26, between two adjacent rows 26 of fins 20, or the like, or a combination or sub-combination thereof. In some embodiments, the channel 27 and the gap 36 may refer to the same location on the upper surface 14 of the substrate 12.

Referring to FIG. 7, in an embodiment of the heat sink 10 the plurality of dimples 28 have a parabolic shape, such as a concave or convex parabolic shape. For example, the plurality of dimples 28 include a central axis that extends upwards from the upper surface 14 to a peak 37, and side surfaces 39. The side surface 39 have a parabolic shape in which outer edges of the side surfaces 39 are the vertices of the parabolic shapes and are tangent to the upper surface 14. In other words, the side surfaces 39 the plurality of dimples 28 are concaved or convex parabolas that merge at the peak 37. The parabolic shape is an efficient shape for improving the heat transfer efficiency of the heat sink 10 because of the increase surface area with a relatively small cross-sectional profile in the direction of the fluid flow F, the rows 26 of the fins 20, or from the first side 16 to the second side 18, or the like. Referring to FIGS. 8A-8D, in an embodiment of the heat sink 10 the plurality of dimples 28 have an airfoil shape. The airfoil shape may be symmetrical, asymmetrical, flat bottom, cambered, or the like, or a combination or sub-combination thereof. In some embodiments, the plurality of dimples 28 may have a shape or cross-sectional profile including a rectangular, prismatic, elliptical, tear-drop, circular, conical, or other known shapes, or the like, or a combination or sub-combination thereof.

In an embodiment, the heat sink 10 includes a combination of the plurality of dimples 28 having different shapes and/or cross-sectional areas. In other words, the plurality of dimples 28 may include a first shape and a second shape. For example, the plurality of dimples 28 having a hemispherical shape, a parabolic shape, and an airfoil shape may be located between at least two rows 26 of the fins 20, in at least one channel 27, and/or in at least one gap 36. The plurality of dimples 28 between the at least two rows 26, in the channel 27, and/or in at least one gap 36 may transition from the hemispherical shape adjacent the first side 16, to the parabolic shape at a point between the first side 16 and the second side 18, and then to the airfoil shape adjacent the second side 18, or the like. The plurality of dimples 28 between the at least two rows 26, in the channel 27, and/or in at least one gap 36 may be arranged in a pattern from the first side 16 to the second side 18, or a point between the first side 16 and the second side 18. For example, the plurality of dimples 28 may have the first arrangement 30a, wherein the first row 32a includes the plurality of dimples 28 with hemispherical shapes and the second row 32b includes plurality of dimples 28 with parabolic shapes. In another example, the first row 32a and the second row 32b may both include the plurality of dimples 28 with the symmetrical airfoil shape and the asymmetrical shape arranged in an alternating pattern within the first row 32a and the second row 32b (e.g., the first row 32a may include the alternating pattern of the plurality of dimples 28 with the symmetrical shape and then the asymmetrical shape).

In some embodiments, the plurality of dimples 28 between the at least two rows 26, in the channel 27, and/or in at least one gap 36 may arranged to guide the fluid flow F within the at least one row 26. Between the at least two rows 26, in the channel 27, and/or in at least one gap 36, the plurality of dimples 28 may include a combination of shapes for controlling the fluid velocity, flow rate, flow type, or other fluid dynamics, or the like. For example, the combination of airfoil shapes may be used increase convective heat transfer by guiding the fluid towards the fins 20, increasing fluid velocity or flow rate adjacent the fins 20, or preventing or reducing fluid velocity reversal and/or flow separation, or the like or a combination or sub-combination thereof. In other words, the plurality of dimples 28 with the asymmetrical, flat bottom, or chambered shape may be disposed adjacent to or in close proximity to the fins 20 to control the dynamics of the fluid. For example, referring to FIG. 4, the combination of plurality of dimples 28 may control the dynamics of the fluid adjacent to the concave and convex portions of the fins 20 and/or spaced apart from the fins 20 (i.e., within the center of the channel 27). In yet a further example, referring to FIGS. 2 and 5-6, the combination of the plurality of dimples 28 may prevent or reduce fluid velocity reversal and/or flow separation between the ends 34 of the fins 20.

Referring to FIGS. 7 and 8A, in an embodiment of the heat sink 10 the plurality of dimples 28 have a dimple height 38 and a dimple length 40. The dimple height 38 of the plurality of dimples 28 may be defined as a percentage of a fin height 42 (i.e., the distance between the base 22 and the tip 24 of the fins 20). In some embodiments, the dimple height 38 is less than the fin height 42. In some embodiments, the dimple height 38 may be greater than zero percent and less than five percent of the fin height 42, greater than or less than 5-10, 10-25, 25-50, or 50-75 percent of the fin height 42, or the like, or a combination or sub-combination thereof. In some embodiments, the dimple height 38 may be defined by a percentage of a fin width 44. For example, the dimple height 38 may be greater than zero percent and less than five percent of the fin width 44, 5-10, 10-25, 25-50, or 50-75 percent of the fin width 44, or the like, or a combination or sub-combination thereof.

Referring to FIGS. 5-7, in an embodiment the plurality of dimples 28 may extend from the fins 20 spaced apart from the base 22. In other words, the plurality of dimples 28 may extend from the fins 20 at some point between the base 22 and the tip 24. The point between the base 22 and the tip 24 may be defined by a percentage of the fin height 42. For example, the plurality of dimples 28 may extend from the fins 20 at or between 0-10, 10-20, 20-30, 30-50, 50-75, or 75-100 percent of the fin height 42. For example, the plurality of dimples 28 may extend from the fins 20 at or below 30 percent of the fin height 42 (i.e., adjacent the base 22) or at or above 70 percent of the fin height 42 (i.e., adjacent the tip 24). Generally, the fluid flow velocity is lower in regions nears the base 22 or the tip 24 of the fins 20. The inclusions of the plurality of dimples 28 in these low fluid velocity regions increases the surface area of the heat sink 10 without a significant increase in the pressure drop across the heat sink 10. Thus, the plurality of dimples 28 improves the overall heat transfer coefficient of the heat sink 10. In some embodiments the plurality of dimples 28 extends from a side surface 46 of the fins 20. In other words, the plurality of dimples 28 extends outwardly from the side surface 46 of the fins 20 toward the center of the respective channels 27.

In an embodiment, the plurality of dimples 28 may include a common or the same shape with varying dimensions, such as dimple height 38, dimple length 40, or other dimensions (e.g., diameter, radius, chord, camber line), or the like. For example, the plurality of dimples 28 may have a hemispherical shape with some of the plurality of dimples 28 having a first dimple height 38 and/or dimple length 40 that is greater than a second dimple height 38 and/or dimple length 40 of the other plurality of dimples 28. In some embodiments, the plurality of dimples 28 may include a variety of different shapes with different cross-sectional areas, dimple heights 38, dimple lengths 40, or other dimensions. For example, the heat sink 10 may include a plurality of first dimples 28 and a plurality of second dimples 28, wherein the plurality of first dimples 28 have a symmetrical airfoil shape and the plurality of second dimples 28 have a cambered airfoil shape.

Referring to FIG. 8A, in an embodiment the plurality of dimples 28 have a lead end 48 and a tail end 50, wherein the length 40 is defined by a distance between the lead end 48 and the tail end 50. The lead end 48 or the trail end 50 can be orientated to affect the flow of the fluid across the substrate 12. As discussed above, the plurality of dimples 28 may have different shapes and/or cross-sectional areas. The cross-sectional area of the plurality of dimples 28 taken along the length 40 affects the flow of the fluid across or around the plurality of dimples 28. In some embodiments, the cross-sectional area of the plurality of dimples 28 may vary (i.e., increase or decrease) from the lead end 48 to the trail end 50. In some embodiments, the lead end 48 approximately faces the first side 16 and the trail end 50 approximately faces the second side 18. In other words, the lead end 48 is orientated or directed upstream, or towards the fluid flow F, and the trail end 50 is orientated or directed downstream, or is relatively aligned with the fluid flow F. Referring to FIGS. 5 and 6, in some embodiments the lead end 48 and/or the trail end 50 of at least one of the plurality of dimples 28 may be orientated or aligned relative to at least one gap 36 such that flow separation or reversal of the fluid velocity is prevented or reduced by the shape and/or orientation of the at least one of the plurality of dimples 28.

Referring to FIG. 4, an embodiment of the heat sink 10 includes fins 20 that are plate fins with a nonlinear shape (i.e., a shape that is wavy, curvy, sinusoidal, convex, concave, curvilinear, or the like, or defines a peak and/or valley). The nonlinear shape of the fins 20 increases the surface area of the fins 20 and acts as a stiffener of the array of fins 20. As stated previously, the increase in the surface area of the heat sink 10 reduces thermal resistance for conduction and improves the conductive heat transfer of the heat sink 10. The convective heat transfer may also increase without a significant increase in the pressure drop. In some embodiments, the lead end 48 of at least one of the plurality of dimples 28 may be orientated relative to at least one of the plurality of fins 20 such that the trail end 50 faces the side surface 46 of the at least one of the plurality of fins 20. In other words, the lead end 48 of at least one of the plurality of dimples 28 may be orientated tangentially to a curvature of at least one of the plurality of fins 20. For example, at least one of the plurality of dimples 28 may be located between a peak and a valley (as defined by the wavy shape) of at least one of the plurality of fins 20 with a nonlinear shape and the lead end 48 of the at least one of the plurality of dimples 28 may be orientated tangentially to the side surface 46 so as to control the flow of the fluid into, out of, or away from the valley.

The plurality of dimples 28 may be composed of any material capable of transferring heat from the device to the fluid (e.g., copper, aluminum, steel, a metal alloy, or the like). The plurality of dimples 28 may be formed by precision forging, additive manufacturing, die casting, CNC manufacturing, extrusion, or the like. In some embodiments, the plurality of dimples 28 are 3D-printed and formed using additive manufacturing methods, such as with metal powders. In particular, using additive manufacturing allows for a precise, controlled, and repeatable method of manufacturing the plurality of dimples 28 such that the shape, size, and arrangement of the plurality of dimples 28 and/or rows 32 of the plurality of dimples 28 are consistent with the desired heat transfer, fluid flow properties, and pressure drop, or the like.

While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes can be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments can be combined to form further embodiments of the invention that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics can be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes can include, but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, to the extent any embodiments are described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics, these embodiments are not outside the scope of the disclosure and can be desirable for particular applications.